Question

数学题目求解，需要过程

①lin (4+1 /x∧3)(7-1/x∧2)
x→∞
②lin (5x∧2)/(x+2)
x→∞
③lin ((2x+1)∧2(3x+1)∧3)/(x-1)∧5
x→∞

Answer 1

1.lin 1/x=0，原式=28
2.lin 5x^2/(x+2)=lin 5(x^2-4)/(x+2)+lin 5*4/(x+2)=lin 5(x-2)+lin 5*4/(x+2)
其中 lin 5*4/(x+2)=0
原式=lin 5(x-2)=∞
3.原式=lin ((2x+1)/(x-1))^2*((3x+1)/(x-1))^3
分式两边各除以x，
原式=lin ((2+1/x)/(1-1/x))^2*((3+1/x)/(1-1/x))^3
lin 1/x=0,
等式=108

Answer 2

1、原式=4/7
2、原式=∞
3、原式=lim(x->∞) (4x^2+4x+1)(27x^3+...+1)/(x^5-...-1)
=lim(x->∞) (108x^5+...+1)/(x^5-...-1)
=lim(x->∞) (108+...+1/x^5)/(1-...-1/x^5)
=108

Answer 3

1、4/7
2、∞
3、=lim(x->∞) (108x^5+...+1)/(x^5-...-1)
=lim(x->∞) (108+...+1/x^5)/(1-...-1/x^5)
=108

Answer 4

1，原式=28，
其他同上

Answer 5

28
∞

108